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OmniTools

Free online calculators

Every calculation you need, running entirely on your machine.

Loan, tax, margin, unit, image, and developer tools for people who would rather not upload a payslip, invoice, or identity document to a stranger's server. Nothing you enter leaves your device.

  • No account needed
  • Nothing uploaded
  • Free, no limits

Find a tool in one step

OmniTools is a free suite of 76 calculators and converters that run inside your web browser. No account, no uploads, no limits.

See all 76 tools

  • Nothing is uploaded

    There is no upload endpoint anywhere on this site. Images, text, and numbers are processed by JavaScript on your own device, so we never receive them and cannot leak them.

  • Instant, offline-capable

    Results appear as you type. Once a page has loaded the tools keep working without a connection, because there is no server round trip to wait for.

  • No account, ever

    No sign-up means no email address, no password, and no personal data attached to your use of a tool. We have nothing to breach because we hold nothing.

Most used tools

The eight calculators people come back to most, covering the four questions that come up constantly: what a loan costs, what a discount does to a margin, what a tax rate adds, and what a unit converts to.

How a tool works here

A calculator that asks you to upload a document to get an answer has already made a decision about your data that you did not get to make. These tools are built so that there is no server to upload to in the first place, which is an architectural constraint rather than a policy promise.

The practical consequence is that we can never ask for a password, never show an upload button, and never need to delete your data, because we never receive it. It also means the tools keep working on a poor connection and cost almost nothing to run.

  1. 01

    Pick the tool you need

    Browse by category or use the finder above. Every tool is listed on one page, with no account wall in front of it.

  2. 02

    Enter your figures

    Adjust the inputs and watch the result update as you type. Nothing is submitted, because there is nowhere for it to go.

  3. 03

    Check the method

    Each page explains the formula it used, works through a real example, and states what it does not model, so you can verify rather than trust.

What each category is for

The catalogue is organised by the question you are trying to answer, not by the maths involved.

Finance

Loan, interest and savings calculators. Every figure is computed in your browser, so no financial detail ever reaches a server.

  • Loan EMI Calculator — Work out the monthly payment, total interest and full amortisation schedule for any loan.
  • Compound Interest & SIP Calculator — Project how a recurring monthly investment or a lump sum grows, with a year-by-year breakdown.
  • In-Hand Salary Calculator (CTC to Take-Home) — Convert annual CTC to monthly take-home with employer EPF, gratuity, professional tax, ESI and income tax, comparing the old and new regime.
  • Gratuity Calculator — Statutory gratuity under the Payment of Gratuity Act with the 15/26 formula, the five-year eligibility test and the tax exemption, with the working shown.
  • Credit Card Payoff & Minimum Due Calculator — See how long a card takes to clear on minimum payments, month by month, including 18% GST on the interest, then compare it with a fixed monthly payment.

Business

Pricing, tax and margin tools for sellers and buyers. Useful before checkout, when the numbers still matter.

  • Discount & Profit Margin Calculator — Work out the real margin on a sale, the effect of a discount, and the price you need to charge.
  • GST & VAT Calculator — Add tax to a net price or extract it from a gross price, with a full rate table.
  • Volumetric Weight Calculator — Free volumetric weight calculator for any parcel. Chargeable weight, CBM and billing slab for courier divisors 5000, 6000 and 4000, in your browser.
  • COD vs Prepaid Profit Calculator — Compare cash on delivery and prepaid profit after RTO, forward and reverse freight, handling fees and remittance delay. Finds the break-even RTO rate.
  • Units Per Carton Calculator — Work out units per inner pack and master carton, cartons needed for an order, pallet count and volume efficiency for any product size.
  • Barcode Check Digit Calculator & Validator — Calculate or validate the GS1 Mod-10 check digit for EAN-13, UPC-A, GTIN-8 and ITF-14 codes, in bulk, with the algorithm explained step by step.
  • Reorder Point & Safety Stock Calculator — Calculate your reorder point, safety stock and economic order quantity from lead time and daily usage, with days of cover and the date to reorder by.

Math

Fractions, ratios, bases, algebra and percentages, with the working shown at every step. All calculations run in your browser.

  • Percentage Calculator — Handle every common percentage question: what percent of, percent change, and reverse percentages.
  • Fraction Calculator — Free fraction calculator that adds, subtracts, multiplies and divides fractions with whole numbers, and simplifies the answer to lowest terms.
  • Scientific Calculator — Free online scientific calculator with sin, cos, tan, logarithms, roots, powers, factorials and degrees/radians mode. No signup, keyboard ready.
  • Ratio Calculator — Simplify ratios, scale them up or down and solve proportion problems like A:B = C:D. Step-by-step working shown for cooking, maps and scale models.
  • Number Base Converter — Convert between binary, decimal, hexadecimal, octal and any base from 2 to 36. Shows the positional working for each digit.

Conversion

Length, weight, temperature, volume and data conversion between metric and imperial, plus area formats common in South Asia.

  • Metric & Imperial Unit Converter — Convert length, mass, volume, area, speed and temperature between metric and imperial.
  • Area & Land Size Converter — Convert land and floor area across square metres, feet, acres, hectares and South Asian units.
  • Length Converter — Convert millimetres, centimetres, metres, kilometres, inches, feet, yards and miles in both directions. Exact factors with a reference table.
  • Weight Converter — Convert kilograms, grams, metric tons, pounds, ounces and stones both ways. Exact 2.20462 factor with common-weight reference table.
  • Temperature Converter — Convert Celsius, Fahrenheit and Kelvin instantly, with the exact formula, freezing/boiling points and a comparison chart for common temperatures.
  • Height Converter — Feet, Inches & Centimetres — Convert height between feet, inches and centimetres in either direction. Enter feet and inches together, get cm and the decimal feet value.
  • Volume & Liquid Converter — Convert litres, millilitres, gallons, quarts, cups, fluid ounces and tablespoons. US and imperial measures both supported.
  • Data Size Converter — Convert bits, bytes, KB, MB, GB and TB using both decimal (SI) and binary (IEC) definitions, so file sizes match what your device actually shows.

Date & time

Age and interval calculations with correct handling of leap years and time zones.

  • Age & Date Difference Calculator — Calculate exact age in years, months and days, or the interval between any two dates.
  • Business Days Calculator — Count working days between two dates, add business days, or total a month. Your weekend pattern, your holidays, and the Excel NETWORKDAYS convention.
  • Time Zone Meeting Overlap — Find the hours two cities actually share in a working day, at the date you choose. Real DST offsets, honest no-overlap answers, and a rotation when thin.
  • Order Cut-Off Date Calculator — Work backwards from the date a parcel must arrive to the last day you can order it, through transit, handling days, courier closed days and holidays.
  • Payment Terms Calculator — Turn net 30, EOM and 2/10 net 30 into the date a term actually produces, naming the trigger and showing the 30-day spread one ambiguous clause can hide.
  • Overtime Calculator — India Labour Codes — Overtime under the India Labour Codes, with the daily and weekly routes both shown and the more favourable to the worker applied, as s.27 requires.
  • ISO Week Number Calculator — ISO 8601 week numbers, with the two rival conventions side by side. 2026 has 53 ISO weeks, not 52, so check your 52-week assumption.
  • Payroll Cut-Off Date Builder — Build your payroll month: attendance cut-off, run date, salary credit, TDS by the 7th, EPF and ESI by the 15th, and the LOP divisor.

Image

Resize, compress and convert images to an exact specification. Files are processed on your device and never uploaded.

  • Image Cropper — Crop by dragging, by aspect ratio, by exact pixels, by percentage, by auto-trimming blank edges, or split into a grid of tiles.
  • Compress Image to Exact KB — Hit an exact file-size target such as 20KB, 50KB or 100KB without guessing or losing legibility.
  • Image Resizer to Exact Pixels — Resize to an exact width and height, with a choice of fit, fill, or stretch, plus optional format conversion.
  • Image Format Converter — Convert HEIC, AVIF, WebP, JPEG, PNG or GIF to JPEG, PNG or WebP, including iPhone HEIC photos, with a quality control for lossy formats.
  • Image Metadata Remover — Strip EXIF data from a photo before sharing it, so GPS coordinates, device model and timestamps are not published.
  • Print Size Calculator — Turn pixel dimensions into a print size at any PPI, and see which axis limits the fit to a real sheet of paper.
  • Image Histogram — Four 256-bin histograms with BT.601 luminance, plus a clipping map that shows where highlights actually blow out.
  • EXIF Viewer — A byte-level EXIF reader with no dependency: camera settings, GPS in degrees, and the thumbnail privacy trap, read on device.
  • Favicon Generator — Build a multi-size favicon.ico, apple-touch-icon and web app manifest, then read the ICO back as a hex breakdown.
  • Social Media Image Resizer — Sixteen placements with the part of your image that survives each crop, plus Open Graph tags and the YouTube size correction.
  • Perceptual Image Hash — aHash, dHash and pHash with Hamming distance, calibrated so 32 bits apart is coincidence rather than a match.
  • Product Photo Spec Checker — Check one product photo against marketplace pixel, format and background rules, and see exactly what cannot be measured.
  • BlurHash & LQIP Generator — Encode a BlurHash, a ThumbHash that keeps alpha, or a 24px WebP LQIP. Length depends only on the component count.

Developer

Encoders, generators, formatters and validators. Paste a secret in and it stays in your browser.

Text

Find and strip the characters that are in your text but not on screen. Everything runs in your browser.

  • Invisible Character Remover — Find and remove the characters hiding in your text: zero-width spaces, invisible Unicode, bidirectional overrides and lookalike letters.
  • Social Media Character Counter — Count a post the way each platform counts it: X link weight, grapheme clusters for Instagram, UTF-16 for TikTok, GSM-7 SMS segments.
  • Case Converter for Titles, Sentences & Code — An editorial rules engine, not a toUpperCase call: AP and Chicago small-word tables, acronyms kept as written, brands like iPhone protected, plus camel.
  • URL Slug Generator — A documented RFC 3986 pipeline: pre-map what NFKD will not decompose, strip marks, transliterate Devanagari and Tamil, truncate at a word boundary.
  • Find and Replace with Regex — The replacement half of regex: capture groups, a literal dollar that silently eats text, lookahead, the missing g flag, and a dry run before applying.
  • Text Diff Checker — Compare two texts line by line or word by word, with normalisation first so CRLF, tabs and a BOM do not read as changes, plus unified diff output.
  • Number to Words (Indian System) — Both directions, both numbering systems: lakh, crore, arab and kharab beside million and billion, a proper cheque line, and a words-to-number verifier.
  • Readability Checker & Text Statistics — Five formulas with their assumptions shown, plus word, sentence and reading-time counts. Honest about a syllable heuristic wrong on 5-10% of words.
  • CSV Cleaner — Parses RFC 4180 by hand, detects the delimiter by column-count consistency not frequency, reports ragged rows by index, keeps destructive fixes off.

PDF

Merge, split, rotate, crop and stamp PDF pages, and inspect what a file actually contains. Your file is opened in this tab and never uploaded.

  • PDF Page Counter & Info — Count pages, measure the page size in points and millimetres, read the version, list metadata and check whether fonts are embedded. Nothing is uploaded.
  • PDF Metadata Remover & Editor — Read, edit or remove the author, title, creator, producer and timestamps a PDF declares about itself, and see what a remover leaves behind.
  • Merge PDF Files — Combine any number of PDFs into one document, in an order you set by dragging. Runs in your browser, so nothing is uploaded.
  • JPG to PDF Converter — Turn JPG, PNG and WebP images into a single multi-page PDF, with correct A4 or Letter sizing and the right resolution for print.
  • Split PDF — Pull pages or ranges out of a PDF as separate files, using expressions like 1-3,5 or -3. The matching pages are previewed before anything is written.
  • Delete PDF Pages — Remove pages you do not want and keep the rest, with a live preview of what will be removed. The reverse action is one click, because deletion has no undo.
  • Rotate PDF Pages — Rotate all pages or just the sideways ones, and see beforehand whether a page is genuinely landscape or merely flagged as rotated.
  • Crop PDF Pages — Trim white margins, crop to a photo or card size, or set the crop and trim boxes a print shop reads. Auto-trim detects the content edge.
  • Change PDF Page Size — Convert a PDF between A4, US Letter, Legal and custom sizes, scaling the content to fit and centring it rather than cropping the edges off.
  • Add Page Numbers to PDF — Number the pages of a PDF as 7 or as page 7 of 42, in roman or letters, starting anywhere, skipping the cover and placing each number precisely.
  • Watermark PDF — Stamp a text or image watermark behind your page content, tiled so it cannot be cropped away. Notes honestly that any watermark can be removed.
  • Flatten PDF — Bake form fields and annotations into the page so a document prints and opens identically everywhere. Lists exactly what it will remove first.

Questions people get wrong

Most mistakes with these tools come from reversing a relationship or picking the wrong base. These are the four that come up most.

Markup vs margin: which should I use?

Use margin when you need to cover overheads, because overheads are a share of revenue. Use markup only when comparing two purchase costs.

MeasureFormulaCost 60, price 100
Markupprofit / cost66.7%
Marginprofit / selling price40%

Removing tax from a price: which way do I divide?

To take tax out of a gross price, divide by one plus the rate. The common shortcut of subtracting the percentage is wrong, because the tax was never charged on the full gross figure.

MethodWorkingNet from 1,180 at 18%
Correct1,180 / 1.181,000.00
Incorrect1,180 x 0.82967.60

Resizing an image: fit, fill, or stretch?

It depends on whether you would rather keep the whole picture, fill the box, or accept distortion. A 4:3 source resized into a 200x230 target has incompatible ratios, so one of those three things has to give.

ModeKeeps aspect ratio4000x3000 to 200x230
FitYes200x150, letterboxed
FillYes200x230, cropped
StretchNo200x230, distorted

Lump sum or SIP: which grows faster?

A lump sum wins on raw return because it is invested for the whole period, but a SIP lowers the risk of investing badly at the wrong moment. The two examples below are not comparable, since the outlay differs; compare them on the multiple of money invested instead.

ApproachInvestedFinalMultiple
EMI, 300,000 at 8.5% over 20 years624,8330cost, not growth
SIP, 10,000/month at 12% over 15 years1,800,0004,995,8022.78x

A loan is not an investment, so an EMI has no final balance to grow into. The rows are shown together only to contrast repayment with compounding.

How we handle accuracy

A tool that is confidently wrong is worse than no tool, so each one is built around a documented method rather than a plausible-looking formula. Every page states what the tool does not model, and where a figure depends on something we cannot verify, the page says so rather than presenting a number as authoritative.

Corrections are treated as bugs, not opinions. If a published calculation is wrong, we fix it and say so.

What every tool page states

  • The formula or method used, in plain language
  • A worked example with real numbers
  • Accuracy and limitations, listed explicitly
  • Answers to the questions people actually ask
  • Confirmation that processing happens in your browser
Read how OmniTools works

Frequently asked questions

Is OmniTools really free?
Yes. Every tool is free with no usage cap, no watermark, and no paid tier. The site is funded by advertising, which is why no feature is ever locked behind a paywall.
Do my files get uploaded?
No. There is no upload endpoint anywhere on this site. Every tool executes in your browser, so images, text, and numbers you enter never reach a server.
Do I need an account?
No. There is no sign-up, no email address, and no password, because there is nothing for us to store about you.
Can I use these tools offline?
Once a page has loaded, yes. Because all the computation happens locally, the tools keep working without an internet connection.
Are the results accurate?
Each tool documents the formula it uses and the assumptions it makes, and states its limitations explicitly. For anything affecting a financial, legal, or regulatory decision, verify against an authoritative current source. We are not a financial, legal, or medical authority.
Why is there no PDF-to-Word converter or background remover?
Both need a real rendering or machine-learning model, and both are usually offered by uploading your file to someone else's computer. We ship the PDF operations that genuinely work in a browser tab and say plainly which ones those are, rather than adding a tool that breaks the privacy claim. PDF-to-Word, PDF-to-JPG, real compression and unlocking all need a server.
What is the difference between markup and margin?
Markup is profit divided by cost, margin is profit divided by selling price. On a cost of 60 sold for 100, markup is 66.7% but margin is only 40%. Sellers covering overheads need the margin figure, because overheads are a share of revenue rather than of cost.
Why does a 50% loss not cancel out with a 50% gain?
Because the base changes each time. Losing 50% of 100 leaves 50, and a 50% gain on 50 adds only 25, giving 75. Losses always need a larger percentage gain to undo, which is why recovering from a loss is harder than earning the same gain in the first place.
Why does my EMI differ from the lender's figure?
Usually because fees are excluded, or because the lender applies a slightly different rate convention. Compare the total interest from our calculator against the lender's total, not the monthly instalment, since a lower instalment often just means a longer term.
Can I use OmniTools results for my tax return?
Use them as a working figure only. Tax rates change and category rules differ by jurisdiction, and the tool does not handle exemptions, reverse charge, or multi-component invoices. Confirm the final figure with your accounting system before filing.
How do you make money if the tools are free?
Advertising, and nothing else. We do not sell data, because we do not collect any, and we do not charge for features. There is no upsell path out of a tool.
I found a calculation that looks wrong. What should I do?
Tell us through the contact page with your inputs, what the tool returned, and what you expected. We treat these as bugs and fix them. Corrections to published tools are the fastest kind of feedback to act on.

Start with a single figure

Open a tool, enter one number, and get the answer. No account, no upload, no watermark.

Browse all 76 toolsLoan EMI calculator